<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #box {
            width: 500px;
            height: 100px;
            border: 2px solid rosybrown;
        }
    </style>

</head>

<body>
    <input type="text">&nbsp;
    <button onclick="cp()">复制</button>
    <div id="box">
    </div>
    <script>
        function cp() {
            var inputText = document.querySelector("input").value;
            var div = document.querySelector("#box");
            var span = document.createElement("span");
            div.appendChild(span)
            }
        }
    </script>
</body>

</html>